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Ann Arbor, MI 48106 PERFORMANCE OF TRAFFIC-ALERT COLLISION AVOIDANCE (TCAS) ANTENNAS IN THE PRESENCE OF SCATTERERS A Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of the Ohio State University by Krishna S. Sampath, B.Tech., M.Tech., M.S. * * + * * The Ohio State University 1993 Dissertation Committee: Approved by: Professor Walter D. Burnside Professor Benedikt A. Munk Advisor Department of Electrical Professor Robert Lee Engineering DEDICATION to my grandparents ACKNOWLEDGMENTS It has been a long and arduous journey through the graduate school, and a number of people have assisted my passage. I would like to express gratitude to my adviser, Professor Walter D. Burnside, for his patience and insight. I want to thank my supervisor Dr. Roberto G. Rojas for his help and training during the formative years. I will always be indebted to Professor Edward H. Newman and Dr. Harry T. Shamansky, whose support and encouragement during the latter years enabled me complete this work. I am grateful to our sponsors, NASA Langley Research Center, Hampton VA, and MIT Lincoln Laboratory, Cambridge MA, for funding the TCAS and HARP programs. Thanks are due to Professors Benedikt A. Munk and Robert Lee for their suggestions. I would also like to thank Dr. Vandana Mohan Raj for helping me stay focussed. Last but not least, my sincere thanks to my parents for their love and understanding. VITA Septem ber 18, 1963 ................................... Born in Chittoor, India. June, 1984 ....................................................B.Tech., Jawaharlal Nehru Technological University, Anantapur, India. June, 1985 - December 1986 ................. M.Tech., Indian Institute of Technology, Kharagpur, India. January 1987 - July 1987 ....................... Scientist, Society for Applied Microwave and Electronics Engineering and Research, Center for Electromagnetics, Madras, India. August 1987 - December 1987 ............. Teaching Assistant, University of Massachusetts, Amherst, MA. January, 1988 - Present ........................... Graduate Research Associate, The Ohio State University, Columbus, OH. PUBLICATIONS Analysis of Airframe Effects on the Performance of TCAS Antennas , co-author R. G. Rojas, Report 724737-1, The Ohio State University ElectroScience Laboratory, August 1992. Analysis and Simulation of Collision Avoidance TCAS Antennas Mounted on Air- cra/fc, co-authors R. G. Rojas and W. D. Burnside, Applied Computational Electro­ magnetics Society Journal , vol. 6(1), pp. 112-139, Summer 1991. Analysis and Simulation of Collision Avoidance TCAS Antennas Mounted on Air­ craft, co-authors R, G. Rojas and W. D. Burnside, Oral Presentation, North Ameri­ can Radio Science Meeting and International IEEE/AP-S Symposium, London On­ tario, June 1991. Modelling and Performance Analysis of Four and Eight Element TCAS, Report 716199-15, The Ohio State University ElectroScience Laboratory, April 1990. Radar Cross Section of a Cylindrically Curved Plate , M. Tech. Thesis, Indian Insti­ tute of Technology, Kharagpur, India, December 1986. FIELDS OF STUDY Major Field: Electrical Engineering Electromagnetic Theory Communication Theory Mathematics TABLE OF CONTENTS DEDICATION............................................................................................. ii ACKNOWLEDGMENTS......................................................................... iii VITA .............................................................................................................. iv LIST OF TABLES....................................................................................... ix LIST OF FIG URES.................................................................................... x CHAPTER PAGE I. INTRODUCTION............................................................................. 1 1.1 Background and M otivation ................................................................. 1 1.2 S y n o p s is ..................................................................................................... 3 II. OPERATION OF T C A S ................................................................. 7 2.1 In tro d u c tio n ............................................................................................... 7 2.2 Comparison of Relative Amplitude System ...................................... 7 2.3 Spiral Phase Antenna System ............................................................. 16 2.4 Results ......................................................................................................... 19 III. OPTIMAL LOCATION OF TCAS ............................................. 34 3.1 In tro d u c tio n ............................................................................................... 34 3.2 Boeing 737-300 ........................................................................................ 35 3.3 Boeing 747-200 ....................................................................................... 40 3.4 Boeing 727-200 ....................................................................................... 43 3.5 Discussion ................................................................................................. 52 IV. EFFECT OF OTHER ANTENNAS .................................................... 55 4.1 Introduction .............................................................................................. 55 4.2 Modeling a Nearby Antenna ............................................................... 56 4.3 L-band AT-741 Blade ............................................................................. 59 4.4 VHF DMC60-1 Blade ............................................................................. 63 4.5 Simulation and Results ......................................................................... 70 V. EFFECT OF ENGINES ........................................................................... 86 5.1 In tro d u c tio n ............................................................................................. 86 5.2 Scattering by a Waveguide ................................................................... 88 5.3 Engine M odel .......................................................................................... 89 5.4 TCAS Performance ................................................................................ 92 VI. CONCLUSION ............................................................................................... 103 6.1 In tro d u c tio n ............................................................................................. 103 6.2 Elevation Effects ................................................................................... 104 6.3 Nearby Antenna Effects ......................................................................... 105 6.4 Engine Effects .......................................................................................... 106 6.5 Other Factors .......................................................................................... 106 6.6 Concluding Remarks ............................................................................ 107 6.6.1 McDonnell Douglas MD-87 ....................................................... 108 6.6.2 Boeing 757-200 ........................................................................... 108 BIBLIOGRAPHY ..................................................................................................... 110 vii APPENDICES A. STATISTICS OF TCAS ANTENNAS.......................................... 113 B. HELICOPTER ANTENNA RADIATION PREDICTION (HARP)............................................................................................. 124 B.l Introduction .............................................................................................. 124 B.2